Planet Minis

melloyello · 06-11-2006, 09:19 PM

What is the difference between a 88cc kit for a z50 and a xr50? On a couple of sites I see different kits for these engines, but why? Are the top ends of these engines really different or not? Does it depend on the year model? If there is a difference what in the world is it?

SHADE · 06-11-2006, 09:31 PM

i dont think there is a difference..JigRacing has a z50 and it had a 72cc and a e22 head with a 20mm carb on it and it was fun fun..

melloyello · 06-11-2006, 09:45 PM

Maybe I read something wrong. I dunno. I just ordered this kit for a build on a 1988 z50 for a local guy. It says z50 82-99. I was just wondering, aren't there 50 motors b/4 82 and why wouldn't this kit fit them?
http://www.dratv.com/600026.html
I also picked up a xr70 carb and intake for free for him. I am going to port the stock head out to match the 70 intake. Well, not really port it, but taper it out so it matches the 70 intake. The kit will be here tomorrow. He just said he wanted me to fix it. Boy will he be surprised. I figured why put it back stock. It's cheaper to build it as a 88cc.
I am also swapping out my loncin 110 for a stock z50 motor tomorrow. I am only doing it b/c my g/f ain't digging the manual clutch. I am probably going w/ the same kit on that one too. Although, I think a 88 race head kit would be a lot more fun in it.

dirtbkr188 · 06-12-2006, 06:47 AM

The '82-'87 Z50R is a long rod 6V engine, and I'm sure you would find the head to be designed differently than that of an XR50. When you get a big bore kit, the piston usually has a slight dome to it, unlike the flat top piston you get with a big bore kit for an XR/CRF50.
I was under the impression that a '93 and newer Z50R engine was identical to the newer XR/CRF ones, which would have a flat top piston, which also leads me to believe that the '88-'92 Z50R has the same head style as the older ones. I've never seen any pictures of the head from either group ( '88-'92 ) or ( '93-'98 ) so, I can't say for sure.
The Z50 engine prior to '82 has a short rod, the piston has a taller deck height, and will not work on an '82 and newer engine.

melloyello · 06-12-2006, 04:27 PM

Well, I just got finished putting the kit in and all went well. Had a little problem fitting the 70 carb under the frame but I got that worked out. Runs good and feels to have good power but the clutch on this thing is slipping so you can't really tell how much more power. If I would have known the clutch was slipping I wouldn't have put the 88 on it b/c it is going to burn that up in no time.
And the kit came w/ a domed piston as opposed to the dished one I took out but there were no clearance issues so all is well.

Fullthrottle · 06-12-2006, 04:49 PM

i've ordered the 2 complete gasket kit for a crf502006 and it fit on a Z50A-K1 1969.

dirtbkr188 · 06-12-2006, 06:59 PM

Quote:

Originally Posted by Fullthrottle

i've ordered the 2 complete gasket kit for a crf502006 and it fit on a Z50A-K1 1969.

Long rod gasket kits will fit on short rod engines...

...clearance isn't an issue with the gaskets...

06-11-2006, 09:19 PM	#1 (permalink)
melloyello 3rd Gear Member Join Date: Jan 2006 Location: williamston, nc Posts: 3,492	z50/xr50 bore kits the same? What is the difference between a 88cc kit for a z50 and a xr50? On a couple of sites I see different kits for these engines, but why? Are the top ends of these engines really different or not? Does it depend on the year model? If there is a difference what in the world is it?

06-11-2006, 09:31 PM	#2 (permalink)
SHADE 3rd Gear Member Join Date: Jan 2005 Location: So*Cal Posts: 6,187 My Mood:	i dont think there is a difference..JigRacing has a z50 and it had a 72cc and a e22 head with a 20mm carb on it and it was fun fun..

06-11-2006, 09:45 PM	#3 (permalink)
melloyello 3rd Gear Member Join Date: Jan 2006 Location: williamston, nc Posts: 3,492	Maybe I read something wrong. I dunno. I just ordered this kit for a build on a 1988 z50 for a local guy. It says z50 82-99. I was just wondering, aren't there 50 motors b/4 82 and why wouldn't this kit fit them? http://www.dratv.com/600026.html I also picked up a xr70 carb and intake for free for him. I am going to port the stock head out to match the 70 intake. Well, not really port it, but taper it out so it matches the 70 intake. The kit will be here tomorrow. He just said he wanted me to fix it. Boy will he be surprised. I figured why put it back stock. It's cheaper to build it as a 88cc. I am also swapping out my loncin 110 for a stock z50 motor tomorrow. I am only doing it b/c my g/f ain't digging the manual clutch. I am probably going w/ the same kit on that one too. Although, I think a 88 race head kit would be a lot more fun in it.

06-12-2006, 06:47 AM	#4 (permalink)
dirtbkr188 3rd Gear Member Join Date: May 2004 Location: New Jersey Posts: 2,972	The '82-'87 Z50R is a long rod 6V engine, and I'm sure you would find the head to be designed differently than that of an XR50. When you get a big bore kit, the piston usually has a slight dome to it, unlike the flat top piston you get with a big bore kit for an XR/CRF50. I was under the impression that a '93 and newer Z50R engine was identical to the newer XR/CRF ones, which would have a flat top piston, which also leads me to believe that the '88-'92 Z50R has the same head style as the older ones. I've never seen any pictures of the head from either group ( '88-'92 ) or ( '93-'98 ) so, I can't say for sure. The Z50 engine prior to '82 has a short rod, the piston has a taller deck height, and will not work on an '82 and newer engine.

06-12-2006, 04:27 PM	#5 (permalink)
melloyello 3rd Gear Member Join Date: Jan 2006 Location: williamston, nc Posts: 3,492	Well, I just got finished putting the kit in and all went well. Had a little problem fitting the 70 carb under the frame but I got that worked out. Runs good and feels to have good power but the clutch on this thing is slipping so you can't really tell how much more power. If I would have known the clutch was slipping I wouldn't have put the 88 on it b/c it is going to burn that up in no time. And the kit came w/ a domed piston as opposed to the dished one I took out but there were no clearance issues so all is well.

06-12-2006, 04:49 PM	#6 (permalink)
Fullthrottle 2nd Gear Member Join Date: Aug 2005 Location: Montréal, Québec, Canada Posts: 424	i've ordered the 2 complete gasket kit for a crf502006 and it fit on a Z50A-K1 1969.

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